Heating, ventilation, and/or air conditioning systems (HVAC systems) are used in residential and/or commercial areas for heating and/or cooling to create comfortable temperatures inside those areas. These temperature controlled areas may be referred to as comfort zones. Some HVAC systems are heat pump systems. Heat pump systems are generally capable of cooling a comfort zone by operating in a cooling mode for transferring heat from a comfort zone to an ambient zone using a refrigeration cycle (i.e., Reverse Rankine cycle). Heat pump systems are also generally capable of reversing the direction of refrigerant flow through the components of the HVAC system so that heat is transferred from the ambient zone to the comfort zone (a heating mode), thereby heating the comfort zone. The efficiency of an HVAC system may be quantified by a coefficient of performance (COP) which is a measure to describe the ratio of useful heat movement to work input, which substantially equates to electrical energy input.